This article is one in a series that have been released in conjunction with Wayne's new book, 101 Performance Projects for Your Porsche Boxster. The book contains 312 pages of full color projects detailing everything from performance mods to changing your brake pads. With more than 950+ full-color glossy photos accompanying extensive step-by-step procedures, this book is required reading in any Boxster owner's collection. The book is currently available and in stock now. See The Official Book Website for more details.
Check out some other sample projects from the book:
Brake discs (or rotors as they are often called) are a very important part of the braking system. The brake pads rub against the discs to create a friction force that is responsible for slowing the car down. If the rotors become too thin, or develop grooves in them, then their ability to stop the car decreases.
When replacing your brake pads, you should always measure the thickness of your brake discs. If they fall below the specified value for your car, then they should be replaced with new ones. Check for grooves in the rotor, and make sure that you take several measurements of the disc in several different places. This will guarantee you that you get an accurate reading. If the brake disc has a groove in it, then it should most certainly be removed and resurfaced by a machine shop, or simply replaced with a new one. Discs with grooves not only brake less efficiently, but they also heat up to higher temperatures, and reduce your overall braking ability.
The measurements that you take with your micrometer should be made from the center of the disc. It is common for OEM rotors to have the minimum thickness stamped on the rotor hub (as is the case with the ceramic PCCB brake option). If you can't find this information, use the following chart to determine if your rotors need to be replaced.
Type and Year.
Min Thickness.
.
Front Vented Steel Rotor (Boxster 1997-2004).
22.6mm.
.
Rear Vented Steel Rotor (Boxster 1997-2004).
18.6mm.
.
Front Vented Steel Rotor (Boxster/Cayman 2005-).
26.0mm.
.
Rear Vented Steel Rotor (Boxster/Cayman 2005-).
22.0mm.
.
If you do find that you need to replace your rotors, the process is a relatively simple one. The procedure for the front or the rear rotors is very similar, but for the sake of this project, we'll look at replacing the rears, which is slightly more complicated due to the addition of the rear parking/emergency brake. With the rear rotors, if the parking brake shoes are very worn, then you may need to back off the adjustment sprocket in order to be able to remove the rear disc (see Project 51 for more details).
The first step is to jack up the car and remove the road wheel. If you haven't already, remove the brake pads from the caliper. Refer to Project 49 on replacing brake pads for more details. The flexible rubber brake hose is attached to the trailing arm of the car via a large clip. This clip retains both the flexible line and the hard line that connects to the rear caliper. Remove this clip so that you will be able to remove the caliper without bending the hard metal brake line.
Now, unbolt the caliper from the trailing arm where it is mounted. There should be two bolts that mount the caliper and hold it in place. After you remove these two bolts, you should be able to slightly move the caliper out of the way of the disc. Exercise caution when moving the caliper around - make sure that you do not let the caliper hang from the rubber brake line, as this will most certainly damage the line.
Once you have the caliper out of the way, remove the small screw that holds on the brake disc. You will need a Phillips head socket tool for this task (you can try using a big screwdriver, but odds are the screw will be on too tight, and you may end up stripping it). At this point, make sure that the parking brake is off. You should now be able to pull the disc off of the hub. If there is any resistance, use a rubber mallet to tap the brake disc off. Sometimes the disc will require some heavy smacks with your rubber mallet to get it off.
If you are having a difficult time getting the disc off, it's probably because the parking brake shoes are stuck on the back of the disc. You might need to adjust the parking brake so that it's not gripping the disc. For more information on this process, see Pelican Technical Article: Parking Brake Adjustment.
Installation of the new brake disc is a snap, simply push it onto the hub. Before you install the new disc, take a close look at your parking brake shoes and see if they warrant replacing. If you can see metal on the shoes, or the previous owner had a hard time remembering to remove the emergency brake, then it might be a good time to replace these. After you install the new discs on both sides, you should test your parking brake and adjust it if necessary. Refer to Project 53 and Project 51 for more details.
After the new disc is installed, replace the retaining screw, reattach the caliper, and install new brake pads. Your new rotors should last a long time, and you should see an improvement in your braking after the wear-in period for your new brake pads.
Figure 1
The front and rear brake discs look almost identical. The rear brake discs have an inner ‘drum' area that acts as the surface for the emergency brake to press against. While the Boxster and Cayman both have disc brakes at all wheels, the rear parking brake mechanism is most similar to a drum brake system. You may want to paint the inner hats and edges of the discs with some high-temp paint. This will keep them from rusting after you install them.
Before you remove your brake discs, it is important to first measure them to see if they need to be replaced. Use a micrometer to perform the measurement. If you use a dial caliper, then you might get a false reading because the disc wears on the area where the pads make contact, not on the edges of the disc. Make sure that you take several measurements in a few different places on the disc in order to compensate for potential low or high spots.
Removal of the caliper is accomplished by unbolting the two hex bolts that mount it to the arm (yellow arrow). The caliper (green arrow) can be pushed out of the away, and doesn't need to be physically disconnected from the brake line. Hang the caliper from a string or coat hanger (blue arrows) so that you don't put unnecessary tension on the rubber brake line (orange arrow).
There are two small locator screws that hold the brake disc in place. Use a big screwdriver or a Phillips head socket tool to remove this screw, and the brake disc should slide off of the hub. Keep in mind that the lug nuts that hold on the wheel apply the majority of the force that constrains the disc to the hub: not this screw.
The new disc can be tapped on with a rubber mallet. If installing the rear discs, make sure that you have your parking brake shoes adjusted away from the inside drum, or they might interfere with the installation of the disc. New discs may not be perfectly flat, and may take a few hundred miles of break-in to achieve their maximum braking efficiency.
Comments: I'm installing OEM rotors. Is there any special preparation or cleaning required on the friction surface?
May 5, 2012
Followup from the Pelican Staff: Nope, they should just be cleaned off with a paper towel, and make sure you don't accidentally spill any motor oil or brake fluid on them. - Wayne at Pelican Parts
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Comments: I thought I saw a comment that there was an article on how to paint the calipers, but now I can't find it. Can you point me to the page if there is one.
